GENUS WISTARIA. 



413 



GENUS WISTARIA. 



This is a small and imperfectly understood genus which consists of four definite and two doubt- 

 ful .speci(>s, all natives of China and Japan. W. chincnsis, the commonest species in cultivation, 

 was studied as a representative of the genus. 



STARCH OF WISTARIA CHINENSIS. (Chart 51.) 



Histological Characteristics. In form the grains are simple and nearly always isolated. The 

 surface of the grains is usually quite regular. The conspicuous forms are oval, rounded oval, and 

 ovoid, with some polygonal, some approaching the reniform type, and some small round grains. 

 (This preparation is very unsatisfactory, as most of the grains are contaminated with so much for- 

 eign material.) 



The hilum may appear in the .small round grains as a centric or slightly eccentric circular cav- 

 ity, but the more numerous elongateil forms have a longitudinal cleft, from which short, radiating 

 fissures sometimes run. 



The lamellce are not usually visible, but in some of the large rounded oval forms 12 rather 

 coarse concentric rings were counted. 



The grains varj' in size from the small, which are 4 by 4//, to the elongated, which are 12 by 10/n 

 in length and breadth. The size of the greater number of grains is about 8 by G/i in length and breadth. 



Polariscopic Properties. -The figure is centric or 

 slightly eccentric, and distinct. Its lines are usually 

 rather thick and fairly clear-cut, may be in the form of 

 a cross, or more commonly of the bean type a longitu- 

 dinal line with bisected ends. 



The degree of polarization is fairly high to high. It 

 often varies in the same aspect of a grain and differs in 

 different aspects of the grain. 



With selenite the quadrants are well defined and com- 

 monly irregular in shape and unequal in size. The colors 

 are fairly bright and generally pure. The blue is occa- 

 sionally not quite pure. The grains of the preparation 

 are so small as to be unsatisfactory for detailed study. 



Iodine Reactions. With 0.25 per cent Lugol's solution 

 the grains color a deep blue-violet, which deepens rapidly; 

 with 0.125 per cent solution most of the grains color 

 immediately a rather light blue-violet, which deepens 

 rather quickly. After heating in water until all the grains 

 are gelatinized, the solution assumes a light olive tint and 

 the grains become a very deep blue on the addition of 

 iodine. If the grains are boiled for 2 minutes ami then treated with iodine, the solution becomes 

 a deep indigo-blue and most of the grain-residues a deep blue, while some are a reddish-blue. When 

 an excess of iodine is added the grain-residues become blue with a retklish tint, while the capsules 

 become a reddish-purple to deep wine color. 



Staining Reactions. With gentian violet and with safranin the grains all begin to stain at once 

 and in 30 minutes they are lightly stained. 



Temperature Reaction. The temperature of gelatinizatlon is 71 to 72 C, mean 71.5. 



Effects of Various Reagents. With chloral hydrate-iodine the reaction begins at once and is 

 over in practically all in a minute. It begins usually at the marginal starch at each end of the grain, 

 the starch becoming dark and swelling slightly. The reaction spreads to other points, from which 

 it advances throughout the grain. It usually proceeds more rapidly in the central than in the mar- 

 ginal portion. The gelatinized grains are not very large and they retain their original form. They 

 are of a uniform dark color, except those portions which have been fi.ssured, where there are light 

 lines of the same shape and size as the fissures. In unfissured grains there arc one or more indistinct 

 light spots which represent the hila. 



With chromic acid reaction begins in a few seconds. It is over in most of the grains in 30 seconds 

 and in all in a minute. The hila or fissures in the region of the hilum become very distinct, and the 



Curve of Reaction-Intensities of Starch of 

 Wistaria chinensis. 



